diff options
Diffstat (limited to 'libgo/go/regexp/regexp.go')
| -rw-r--r-- | libgo/go/regexp/regexp.go | 1011 |
1 files changed, 214 insertions, 797 deletions
diff --git a/libgo/go/regexp/regexp.go b/libgo/go/regexp/regexp.go index e8d4c08..2325f62 100644 --- a/libgo/go/regexp/regexp.go +++ b/libgo/go/regexp/regexp.go @@ -3,27 +3,12 @@ // Package regexp implements a simple regular expression library. // -// The syntax of the regular expressions accepted is: +// The syntax of the regular expressions accepted is the same +// general syntax used by Perl, Python, and other languages. +// More precisely, it is the syntax accepted by RE2 and described at +// http://code.google.com/p/re2/wiki/Syntax, except for \C. // -// regexp: -// concatenation { '|' concatenation } -// concatenation: -// { closure } -// closure: -// term [ '*' | '+' | '?' ] -// term: -// '^' -// '$' -// '.' -// character -// '[' [ '^' ] { character-range } ']' -// '(' regexp ')' -// character-range: -// character [ '-' character ] -// -// All characters are UTF-8-encoded code points. Backslashes escape special -// characters, including inside character classes. The standard Go character -// escapes are also recognized: \a \b \f \n \r \t \v. +// All characters are UTF-8-encoded code points. // // There are 16 methods of Regexp that match a regular expression and identify // the matched text. Their names are matched by this regular expression: @@ -72,7 +57,10 @@ import ( "bytes" "io" "os" + "regexp/syntax" + "strconv" "strings" + "sync" "utf8" ) @@ -85,528 +73,24 @@ func (e Error) String() string { return string(e) } -// Error codes returned by failures to parse an expression. -var ( - ErrInternal = Error("regexp: internal error") - ErrUnmatchedLpar = Error("regexp: unmatched '('") - ErrUnmatchedRpar = Error("regexp: unmatched ')'") - ErrUnmatchedLbkt = Error("regexp: unmatched '['") - ErrUnmatchedRbkt = Error("regexp: unmatched ']'") - ErrBadRange = Error("regexp: bad range in character class") - ErrExtraneousBackslash = Error("regexp: extraneous backslash") - ErrBadClosure = Error("regexp: repeated closure (**, ++, etc.)") - ErrBareClosure = Error("regexp: closure applies to nothing") - ErrBadBackslash = Error("regexp: illegal backslash escape") -) - -const ( - iStart = iota // beginning of program - iEnd // end of program: success - iBOT // '^' beginning of text - iEOT // '$' end of text - iChar // 'a' regular character - iCharClass // [a-z] character class - iAny // '.' any character including newline - iNotNL // [^\n] special case: any character but newline - iBra // '(' parenthesized expression: 2*braNum for left, 2*braNum+1 for right - iAlt // '|' alternation - iNop // do nothing; makes it easy to link without patching -) - -// An instruction executed by the NFA -type instr struct { - kind int // the type of this instruction: iChar, iAny, etc. - index int // used only in debugging; could be eliminated - next *instr // the instruction to execute after this one - // Special fields valid only for some items. - char int // iChar - braNum int // iBra, iEbra - cclass *charClass // iCharClass - left *instr // iAlt, other branch -} - -func (i *instr) print() { - switch i.kind { - case iStart: - print("start") - case iEnd: - print("end") - case iBOT: - print("bot") - case iEOT: - print("eot") - case iChar: - print("char ", string(i.char)) - case iCharClass: - i.cclass.print() - case iAny: - print("any") - case iNotNL: - print("notnl") - case iBra: - if i.braNum&1 == 0 { - print("bra", i.braNum/2) - } else { - print("ebra", i.braNum/2) - } - case iAlt: - print("alt(", i.left.index, ")") - case iNop: - print("nop") - } -} - // Regexp is the representation of a compiled regular expression. // The public interface is entirely through methods. // A Regexp is safe for concurrent use by multiple goroutines. type Regexp struct { - expr string // the original expression - prefix string // initial plain text string - prefixBytes []byte // initial plain text bytes - inst []*instr - start *instr // first instruction of machine - prefixStart *instr // where to start if there is a prefix - nbra int // number of brackets in expression, for subexpressions -} - -type charClass struct { - negate bool // is character class negated? ([^a-z]) - // slice of int, stored pairwise: [a-z] is (a,z); x is (x,x): - ranges []int - cmin, cmax int -} - -func (cclass *charClass) print() { - print("charclass") - if cclass.negate { - print(" (negated)") - } - for i := 0; i < len(cclass.ranges); i += 2 { - l := cclass.ranges[i] - r := cclass.ranges[i+1] - if l == r { - print(" [", string(l), "]") - } else { - print(" [", string(l), "-", string(r), "]") - } - } -} - -func (cclass *charClass) addRange(a, b int) { - // range is a through b inclusive - cclass.ranges = append(cclass.ranges, a, b) - if a < cclass.cmin { - cclass.cmin = a - } - if b > cclass.cmax { - cclass.cmax = b - } -} - -func (cclass *charClass) matches(c int) bool { - if c < cclass.cmin || c > cclass.cmax { - return cclass.negate - } - ranges := cclass.ranges - for i := 0; i < len(ranges); i = i + 2 { - if ranges[i] <= c && c <= ranges[i+1] { - return !cclass.negate - } - } - return cclass.negate -} - -func newCharClass() *instr { - i := &instr{kind: iCharClass} - i.cclass = new(charClass) - i.cclass.ranges = make([]int, 0, 4) - i.cclass.cmin = 0x10FFFF + 1 // MaxRune + 1 - i.cclass.cmax = -1 - return i -} - -func (re *Regexp) add(i *instr) *instr { - i.index = len(re.inst) - re.inst = append(re.inst, i) - return i -} - -type parser struct { - re *Regexp - nlpar int // number of unclosed lpars - pos int - ch int -} - -func (p *parser) error(err Error) { - panic(err) -} - -const endOfText = -1 - -func (p *parser) c() int { return p.ch } - -func (p *parser) nextc() int { - if p.pos >= len(p.re.expr) { - p.ch = endOfText - } else { - c, w := utf8.DecodeRuneInString(p.re.expr[p.pos:]) - p.ch = c - p.pos += w - } - return p.ch -} - -func newParser(re *Regexp) *parser { - p := new(parser) - p.re = re - p.nextc() // load p.ch - return p -} - -func special(c int) bool { - for _, r := range `\.+*?()|[]^$` { - if c == r { - return true - } - } - return false -} - -func ispunct(c int) bool { - for _, r := range "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~" { - if c == r { - return true - } - } - return false -} - -var escapes = []byte("abfnrtv") -var escaped = []byte("\a\b\f\n\r\t\v") - -func escape(c int) int { - for i, b := range escapes { - if int(b) == c { - return i - } - } - return -1 -} - -func (p *parser) checkBackslash() int { - c := p.c() - if c == '\\' { - c = p.nextc() - switch { - case c == endOfText: - p.error(ErrExtraneousBackslash) - case ispunct(c): - // c is as delivered - case escape(c) >= 0: - c = int(escaped[escape(c)]) - default: - p.error(ErrBadBackslash) - } - } - return c -} - -func (p *parser) charClass() *instr { - i := newCharClass() - cc := i.cclass - if p.c() == '^' { - cc.negate = true - p.nextc() - } - left := -1 - for { - switch c := p.c(); c { - case ']', endOfText: - if left >= 0 { - p.error(ErrBadRange) - } - // Is it [^\n]? - if cc.negate && len(cc.ranges) == 2 && - cc.ranges[0] == '\n' && cc.ranges[1] == '\n' { - nl := &instr{kind: iNotNL} - p.re.add(nl) - return nl - } - // Special common case: "[a]" -> "a" - if !cc.negate && len(cc.ranges) == 2 && cc.ranges[0] == cc.ranges[1] { - c := &instr{kind: iChar, char: cc.ranges[0]} - p.re.add(c) - return c - } - p.re.add(i) - return i - case '-': // do this before backslash processing - p.error(ErrBadRange) - default: - c = p.checkBackslash() - p.nextc() - switch { - case left < 0: // first of pair - if p.c() == '-' { // range - p.nextc() - left = c - } else { // single char - cc.addRange(c, c) - } - case left <= c: // second of pair - cc.addRange(left, c) - left = -1 - default: - p.error(ErrBadRange) - } - } - } - panic("unreachable") -} - -func (p *parser) term() (start, end *instr) { - switch c := p.c(); c { - case '|', endOfText: - return nil, nil - case '*', '+', '?': - p.error(ErrBareClosure) - case ')': - if p.nlpar == 0 { - p.error(ErrUnmatchedRpar) - } - return nil, nil - case ']': - p.error(ErrUnmatchedRbkt) - case '^': - p.nextc() - start = p.re.add(&instr{kind: iBOT}) - return start, start - case '$': - p.nextc() - start = p.re.add(&instr{kind: iEOT}) - return start, start - case '.': - p.nextc() - start = p.re.add(&instr{kind: iAny}) - return start, start - case '[': - p.nextc() - start = p.charClass() - if p.c() != ']' { - p.error(ErrUnmatchedLbkt) - } - p.nextc() - return start, start - case '(': - p.nextc() - p.nlpar++ - p.re.nbra++ // increment first so first subexpr is \1 - nbra := p.re.nbra - start, end = p.regexp() - if p.c() != ')' { - p.error(ErrUnmatchedLpar) - } - p.nlpar-- - p.nextc() - bra := &instr{kind: iBra, braNum: 2 * nbra} - p.re.add(bra) - ebra := &instr{kind: iBra, braNum: 2*nbra + 1} - p.re.add(ebra) - if start == nil { - if end == nil { - p.error(ErrInternal) - return - } - start = ebra - } else { - end.next = ebra - } - bra.next = start - return bra, ebra - default: - c = p.checkBackslash() - p.nextc() - start = &instr{kind: iChar, char: c} - p.re.add(start) - return start, start - } - panic("unreachable") -} - -func (p *parser) closure() (start, end *instr) { - start, end = p.term() - if start == nil { - return - } - switch p.c() { - case '*': - // (start,end)*: - alt := &instr{kind: iAlt} - p.re.add(alt) - end.next = alt // after end, do alt - alt.left = start // alternate brach: return to start - start = alt // alt becomes new (start, end) - end = alt - case '+': - // (start,end)+: - alt := &instr{kind: iAlt} - p.re.add(alt) - end.next = alt // after end, do alt - alt.left = start // alternate brach: return to start - end = alt // start is unchanged; end is alt - case '?': - // (start,end)?: - alt := &instr{kind: iAlt} - p.re.add(alt) - nop := &instr{kind: iNop} - p.re.add(nop) - alt.left = start // alternate branch is start - alt.next = nop // follow on to nop - end.next = nop // after end, go to nop - start = alt // start is now alt - end = nop // end is nop pointed to by both branches - default: - return - } - switch p.nextc() { - case '*', '+', '?': - p.error(ErrBadClosure) - } - return -} - -func (p *parser) concatenation() (start, end *instr) { - for { - nstart, nend := p.closure() - switch { - case nstart == nil: // end of this concatenation - if start == nil { // this is the empty string - nop := p.re.add(&instr{kind: iNop}) - return nop, nop - } - return - case start == nil: // this is first element of concatenation - start, end = nstart, nend - default: - end.next = nstart - end = nend - } - } - panic("unreachable") -} - -func (p *parser) regexp() (start, end *instr) { - start, end = p.concatenation() - for { - switch p.c() { - default: - return - case '|': - p.nextc() - nstart, nend := p.concatenation() - alt := &instr{kind: iAlt} - p.re.add(alt) - alt.left = start - alt.next = nstart - nop := &instr{kind: iNop} - p.re.add(nop) - end.next = nop - nend.next = nop - start, end = alt, nop - } - } - panic("unreachable") -} - -func unNop(i *instr) *instr { - for i.kind == iNop { - i = i.next - } - return i -} - -func (re *Regexp) eliminateNops() { - for _, inst := range re.inst { - if inst.kind == iEnd { - continue - } - inst.next = unNop(inst.next) - if inst.kind == iAlt { - inst.left = unNop(inst.left) - } - } -} - -func (re *Regexp) dump() { - print("prefix <", re.prefix, ">\n") - for _, inst := range re.inst { - print(inst.index, ": ") - inst.print() - if inst.kind != iEnd { - print(" -> ", inst.next.index) - } - print("\n") - } -} - -func (re *Regexp) doParse() { - p := newParser(re) - start := &instr{kind: iStart} - re.add(start) - s, e := p.regexp() - start.next = s - re.start = start - e.next = re.add(&instr{kind: iEnd}) - - if debug { - re.dump() - println() - } - - re.eliminateNops() - if debug { - re.dump() - println() - } - re.setPrefix() - if debug { - re.dump() - println() - } -} - -// Extract regular text from the beginning of the pattern, -// possibly after a leading iBOT. -// That text can be used by doExecute to speed up matching. -func (re *Regexp) setPrefix() { - var b []byte - var utf = make([]byte, utf8.UTFMax) - var inst *instr - // First instruction is start; skip that. Also skip any initial iBOT. - inst = re.inst[0].next - for inst.kind == iBOT { - inst = inst.next - } -Loop: - for ; inst.kind != iEnd; inst = inst.next { - // stop if this is not a char - if inst.kind != iChar { - break - } - // stop if this char can be followed by a match for an empty string, - // which includes closures, ^, and $. - switch inst.next.kind { - case iBOT, iEOT, iAlt: - break Loop - } - n := utf8.EncodeRune(utf, inst.char) - b = append(b, utf[0:n]...) - } - // point prefixStart instruction to first non-CHAR after prefix - re.prefixStart = inst - re.prefixBytes = b - re.prefix = string(b) + // read-only after Compile + expr string // as passed to Compile + prog *syntax.Prog // compiled program + prefix string // required prefix in unanchored matches + prefixBytes []byte // prefix, as a []byte + prefixComplete bool // prefix is the entire regexp + prefixRune int // first rune in prefix + cond syntax.EmptyOp // empty-width conditions required at start of match + numSubexp int + longest bool + + // cache of machines for running regexp + mu sync.Mutex + machine []*machine } // String returns the source text used to compile the regular expression. @@ -614,21 +98,96 @@ func (re *Regexp) String() string { return re.expr } -// Compile parses a regular expression and returns, if successful, a Regexp -// object that can be used to match against text. -func Compile(str string) (regexp *Regexp, error os.Error) { - regexp = new(Regexp) - // doParse will panic if there is a parse error. - defer func() { - if e := recover(); e != nil { - regexp = nil - error = e.(Error) // Will re-panic if error was not an Error, e.g. nil-pointer exception - } - }() - regexp.expr = str - regexp.inst = make([]*instr, 0, 10) - regexp.doParse() - return +// Compile parses a regular expression and returns, if successful, +// a Regexp object that can be used to match against text. +// +// When matching against text, the regexp returns a match that +// begins as early as possible in the input (leftmost), and among those +// it chooses the one that a backtracking search would have found first. +// This so-called leftmost-first matching is the same semantics +// that Perl, Python, and other implementations use, although this +// package implements it without the expense of backtracking. +// For POSIX leftmost-longest matching, see CompilePOSIX. +func Compile(expr string) (*Regexp, os.Error) { + return compile(expr, syntax.Perl, false) +} + +// CompilePOSIX is like Compile but restricts the regular expression +// to POSIX ERE (egrep) syntax and changes the match semantics to +// leftmost-longest. +// +// That is, when matching against text, the regexp returns a match that +// begins as early as possible in the input (leftmost), and among those +// it chooses a match that is as long as possible. +// This so-called leftmost-longest matching is the same semantics +// that early regular expression implementations used and that POSIX +// specifies. +// +// However, there can be multiple leftmost-longest matches, with different +// submatch choices, and here this package diverges from POSIX. +// Among the possible leftmost-longest matches, this package chooses +// the one that a backtracking search would have found first, while POSIX +// specifies that the match be chosen to maximize the length of the first +// subexpression, then the second, and so on from left to right. +// The POSIX rule is computationally prohibitive and not even well-defined. +// See http://swtch.com/~rsc/regexp/regexp2.html#posix for details. +func CompilePOSIX(expr string) (*Regexp, os.Error) { + return compile(expr, syntax.POSIX, true) +} + +func compile(expr string, mode syntax.Flags, longest bool) (*Regexp, os.Error) { + re, err := syntax.Parse(expr, mode) + if err != nil { + return nil, err + } + maxCap := re.MaxCap() + re = re.Simplify() + prog, err := syntax.Compile(re) + if err != nil { + return nil, err + } + regexp := &Regexp{ + expr: expr, + prog: prog, + numSubexp: maxCap, + cond: prog.StartCond(), + longest: longest, + } + regexp.prefix, regexp.prefixComplete = prog.Prefix() + if regexp.prefix != "" { + // TODO(rsc): Remove this allocation by adding + // IndexString to package bytes. + regexp.prefixBytes = []byte(regexp.prefix) + regexp.prefixRune, _ = utf8.DecodeRuneInString(regexp.prefix) + } + return regexp, nil +} + +// get returns a machine to use for matching re. +// It uses the re's machine cache if possible, to avoid +// unnecessary allocation. +func (re *Regexp) get() *machine { + re.mu.Lock() + if n := len(re.machine); n > 0 { + z := re.machine[n-1] + re.machine = re.machine[:n-1] + re.mu.Unlock() + return z + } + re.mu.Unlock() + z := progMachine(re.prog) + z.re = re + return z +} + +// put returns a machine to the re's machine cache. +// There is no attempt to limit the size of the cache, so it will +// grow to the maximum number of simultaneous matches +// run using re. (The cache empties when re gets garbage collected.) +func (re *Regexp) put(z *machine) { + re.mu.Lock() + re.machine = append(re.machine, z) + re.mu.Unlock() } // MustCompile is like Compile but panics if the expression cannot be parsed. @@ -637,116 +196,35 @@ func Compile(str string) (regexp *Regexp, error os.Error) { func MustCompile(str string) *Regexp { regexp, error := Compile(str) if error != nil { - panic(`regexp: compiling "` + str + `": ` + error.String()) + panic(`regexp: Compile(` + quote(str) + `): ` + error.String()) } return regexp } -// NumSubexp returns the number of parenthesized subexpressions in this Regexp. -func (re *Regexp) NumSubexp() int { return re.nbra } - -// The match arena allows us to reduce the garbage generated by tossing -// match vectors away as we execute. Matches are ref counted and returned -// to a free list when no longer active. Increases a simple benchmark by 22X. -type matchArena struct { - head *matchVec - len int // length of match vector - pos int - atBOT bool // whether we're at beginning of text - atEOT bool // whether we're at end of text -} - -type matchVec struct { - m []int // pairs of bracketing submatches. 0th is start,end - ref int - next *matchVec -} - -func (a *matchArena) new() *matchVec { - if a.head == nil { - const N = 10 - block := make([]matchVec, N) - for i := 0; i < N; i++ { - b := &block[i] - b.next = a.head - a.head = b - } - } - m := a.head - a.head = m.next - m.ref = 0 - if m.m == nil { - m.m = make([]int, a.len) - } - return m -} - -func (a *matchArena) free(m *matchVec) { - m.ref-- - if m.ref == 0 { - m.next = a.head - a.head = m +// MustCompilePOSIX is like CompilePOSIX but panics if the expression cannot be parsed. +// It simplifies safe initialization of global variables holding compiled regular +// expressions. +func MustCompilePOSIX(str string) *Regexp { + regexp, error := CompilePOSIX(str) + if error != nil { + panic(`regexp: CompilePOSIX(` + quote(str) + `): ` + error.String()) } + return regexp } -func (a *matchArena) copy(m *matchVec) *matchVec { - m1 := a.new() - copy(m1.m, m.m) - return m1 -} - -func (a *matchArena) noMatch() *matchVec { - m := a.new() - for i := range m.m { - m.m[i] = -1 // no match seen; catches cases like "a(b)?c" on "ac" +func quote(s string) string { + if strconv.CanBackquote(s) { + return "`" + s + "`" } - m.ref = 1 - return m + return strconv.Quote(s) } -type state struct { - inst *instr // next instruction to execute - prefixed bool // this match began with a fixed prefix - match *matchVec +// NumSubexp returns the number of parenthesized subexpressions in this Regexp. +func (re *Regexp) NumSubexp() int { + return re.numSubexp } -// Append new state to to-do list. Leftmost-longest wins so avoid -// adding a state that's already active. The matchVec will be inc-ref'ed -// if it is assigned to a state. -func (a *matchArena) addState(s []state, inst *instr, prefixed bool, match *matchVec) []state { - switch inst.kind { - case iBOT: - if a.atBOT { - s = a.addState(s, inst.next, prefixed, match) - } - return s - case iEOT: - if a.atEOT { - s = a.addState(s, inst.next, prefixed, match) - } - return s - case iBra: - match.m[inst.braNum] = a.pos - s = a.addState(s, inst.next, prefixed, match) - return s - } - l := len(s) - // States are inserted in order so it's sufficient to see if we have the same - // instruction; no need to see if existing match is earlier (it is). - for i := 0; i < l; i++ { - if s[i].inst == inst { - return s - } - } - s = append(s, state{inst, prefixed, match}) - match.ref++ - if inst.kind == iAlt { - s = a.addState(s, inst.left, prefixed, a.copy(match)) - // give other branch a copy of this match vector - s = a.addState(s, inst.next, prefixed, a.copy(match)) - } - return s -} +const endOfText = -1 // input abstracts different representations of the input text. It provides // one-character lookahead. @@ -755,6 +233,7 @@ type input interface { canCheckPrefix() bool // can we look ahead without losing info? hasPrefix(re *Regexp) bool index(re *Regexp, pos int) int + context(pos int) syntax.EmptyOp } // inputString scans a string. @@ -768,7 +247,11 @@ func newInputString(str string) *inputString { func (i *inputString) step(pos int) (int, int) { if pos < len(i.str) { - return utf8.DecodeRuneInString(i.str[pos:len(i.str)]) + c := i.str[pos] + if c < utf8.RuneSelf { + return int(c), 1 + } + return utf8.DecodeRuneInString(i.str[pos:]) } return endOfText, 0 } @@ -785,6 +268,17 @@ func (i *inputString) index(re *Regexp, pos int) int { return strings.Index(i.str[pos:], re.prefix) } +func (i *inputString) context(pos int) syntax.EmptyOp { + r1, r2 := -1, -1 + if pos > 0 && pos <= len(i.str) { + r1, _ = utf8.DecodeLastRuneInString(i.str[:pos]) + } + if pos < len(i.str) { + r2, _ = utf8.DecodeRuneInString(i.str[pos:]) + } + return syntax.EmptyOpContext(r1, r2) +} + // inputBytes scans a byte slice. type inputBytes struct { str []byte @@ -796,7 +290,11 @@ func newInputBytes(str []byte) *inputBytes { func (i *inputBytes) step(pos int) (int, int) { if pos < len(i.str) { - return utf8.DecodeRune(i.str[pos:len(i.str)]) + c := i.str[pos] + if c < utf8.RuneSelf { + return int(c), 1 + } + return utf8.DecodeRune(i.str[pos:]) } return endOfText, 0 } @@ -813,6 +311,17 @@ func (i *inputBytes) index(re *Regexp, pos int) int { return bytes.Index(i.str[pos:], re.prefixBytes) } +func (i *inputBytes) context(pos int) syntax.EmptyOp { + r1, r2 := -1, -1 + if pos > 0 && pos <= len(i.str) { + r1, _ = utf8.DecodeLastRune(i.str[:pos]) + } + if pos < len(i.str) { + r2, _ = utf8.DecodeRune(i.str[pos:]) + } + return syntax.EmptyOpContext(r1, r2) +} + // inputReader scans a RuneReader. type inputReader struct { r io.RuneReader @@ -850,150 +359,35 @@ func (i *inputReader) index(re *Regexp, pos int) int { return -1 } -// Search match starting from pos bytes into the input. -func (re *Regexp) doExecute(i input, pos int) []int { - var s [2][]state - s[0] = make([]state, 0, 10) - s[1] = make([]state, 0, 10) - in, out := 0, 1 - var final state - found := false - anchored := re.inst[0].next.kind == iBOT - if anchored && pos > 0 { - return nil - } - // fast check for initial plain substring - if i.canCheckPrefix() && re.prefix != "" { - advance := 0 - if anchored { - if !i.hasPrefix(re) { - return nil - } - } else { - advance = i.index(re, pos) - if advance == -1 { - return nil - } - } - pos += advance - } - // We look one character ahead so we can match $, which checks whether - // we are at EOT. - nextChar, nextWidth := i.step(pos) - arena := &matchArena{ - len: 2 * (re.nbra + 1), - pos: pos, - atBOT: pos == 0, - atEOT: nextChar == endOfText, - } - for c, startPos := 0, pos; c != endOfText; { - if !found && (pos == startPos || !anchored) { - // prime the pump if we haven't seen a match yet - match := arena.noMatch() - match.m[0] = pos - s[out] = arena.addState(s[out], re.start.next, false, match) - arena.free(match) // if addState saved it, ref was incremented - } else if len(s[out]) == 0 { - // machine has completed - break - } - in, out = out, in // old out state is new in state - // clear out old state - old := s[out] - for _, state := range old { - arena.free(state.match) - } - s[out] = old[0:0] // truncate state vector - c = nextChar - thisPos := pos - pos += nextWidth - nextChar, nextWidth = i.step(pos) - arena.atEOT = nextChar == endOfText - arena.atBOT = false - arena.pos = pos - for _, st := range s[in] { - switch st.inst.kind { - case iBOT: - case iEOT: - case iChar: - if c == st.inst.char { - s[out] = arena.addState(s[out], st.inst.next, st.prefixed, st.match) - } - case iCharClass: - if st.inst.cclass.matches(c) { - s[out] = arena.addState(s[out], st.inst.next, st.prefixed, st.match) - } - case iAny: - if c != endOfText { - s[out] = arena.addState(s[out], st.inst.next, st.prefixed, st.match) - } - case iNotNL: - if c != endOfText && c != '\n' { - s[out] = arena.addState(s[out], st.inst.next, st.prefixed, st.match) - } - case iBra: - case iAlt: - case iEnd: - // choose leftmost longest - if !found || // first - st.match.m[0] < final.match.m[0] || // leftmost - (st.match.m[0] == final.match.m[0] && thisPos > final.match.m[1]) { // longest - if final.match != nil { - arena.free(final.match) - } - final = st - final.match.ref++ - final.match.m[1] = thisPos - } - found = true - default: - st.inst.print() - panic("unknown instruction in execute") - } - } - } - if final.match == nil { - return nil - } - // if match found, back up start of match by width of prefix. - if final.prefixed && len(final.match.m) > 0 { - final.match.m[0] -= len(re.prefix) - } - return final.match.m +func (i *inputReader) context(pos int) syntax.EmptyOp { + return 0 } // LiteralPrefix returns a literal string that must begin any match // of the regular expression re. It returns the boolean true if the // literal string comprises the entire regular expression. func (re *Regexp) LiteralPrefix() (prefix string, complete bool) { - c := make([]int, len(re.inst)-2) // minus start and end. - // First instruction is start; skip that. - i := 0 - for inst := re.inst[0].next; inst.kind != iEnd; inst = inst.next { - // stop if this is not a char - if inst.kind != iChar { - return string(c[:i]), false - } - c[i] = inst.char - i++ - } - return string(c[:i]), true + return re.prefix, re.prefixComplete } // MatchReader returns whether the Regexp matches the text read by the // RuneReader. The return value is a boolean: true for match, false for no // match. func (re *Regexp) MatchReader(r io.RuneReader) bool { - return len(re.doExecute(newInputReader(r), 0)) > 0 + return re.doExecute(newInputReader(r), 0, 0) != nil } // MatchString returns whether the Regexp matches the string s. // The return value is a boolean: true for match, false for no match. -func (re *Regexp) MatchString(s string) bool { return len(re.doExecute(newInputString(s), 0)) > 0 } +func (re *Regexp) MatchString(s string) bool { + return re.doExecute(newInputString(s), 0, 0) != nil +} // Match returns whether the Regexp matches the byte slice b. // The return value is a boolean: true for match, false for no match. -func (re *Regexp) Match(b []byte) bool { return len(re.doExecute(newInputBytes(b), 0)) > 0 } +func (re *Regexp) Match(b []byte) bool { + return re.doExecute(newInputBytes(b), 0, 0) != nil +} // MatchReader checks whether a textual regular expression matches the text // read by the RuneReader. More complicated queries need to use Compile and @@ -1044,7 +438,7 @@ func (re *Regexp) ReplaceAllStringFunc(src string, repl func(string) string) str searchPos := 0 // position where we next look for a match buf := new(bytes.Buffer) for searchPos <= len(src) { - a := re.doExecute(newInputString(src), searchPos) + a := re.doExecute(newInputString(src), searchPos, 2) if len(a) == 0 { break // no more matches } @@ -1096,7 +490,7 @@ func (re *Regexp) ReplaceAllFunc(src []byte, repl func([]byte) []byte) []byte { searchPos := 0 // position where we next look for a match buf := new(bytes.Buffer) for searchPos <= len(src) { - a := re.doExecute(newInputBytes(src), searchPos) + a := re.doExecute(newInputBytes(src), searchPos, 2) if len(a) == 0 { break // no more matches } @@ -1132,6 +526,12 @@ func (re *Regexp) ReplaceAllFunc(src []byte, repl func([]byte) []byte) []byte { return buf.Bytes() } +var specialBytes = []byte(`\.+*?()|[]{}^$`) + +func special(b byte) bool { + return bytes.IndexByte(specialBytes, b) >= 0 +} + // QuoteMeta returns a string that quotes all regular expression metacharacters // inside the argument text; the returned string is a regular expression matching // the literal text. For example, QuoteMeta(`[foo]`) returns `\[foo\]`. @@ -1141,7 +541,7 @@ func QuoteMeta(s string) string { // A byte loop is correct because all metacharacters are ASCII. j := 0 for i := 0; i < len(s); i++ { - if special(int(s[i])) { + if special(s[i]) { b[j] = '\\' j++ } @@ -1151,6 +551,23 @@ func QuoteMeta(s string) string { return string(b[0:j]) } +// The number of capture values in the program may correspond +// to fewer capturing expressions than are in the regexp. +// For example, "(a){0}" turns into an empty program, so the +// maximum capture in the program is 0 but we need to return +// an expression for \1. Pad appends -1s to the slice a as needed. +func (re *Regexp) pad(a []int) []int { + if a == nil { + // No match. + return nil + } + n := (1 + re.numSubexp) * 2 + for len(a) < n { + a = append(a, -1) + } + return a +} + // Find matches in slice b if b is non-nil, otherwise find matches in string s. func (re *Regexp) allMatches(s string, b []byte, n int, deliver func([]int)) { var end int @@ -1167,7 +584,7 @@ func (re *Regexp) allMatches(s string, b []byte, n int, deliver func([]int)) { } else { in = newInputBytes(b) } - matches := re.doExecute(in, pos) + matches := re.doExecute(in, pos, re.prog.NumCap) if len(matches) == 0 { break } @@ -1198,7 +615,7 @@ func (re *Regexp) allMatches(s string, b []byte, n int, deliver func([]int)) { prevMatchEnd = matches[1] if accept { - deliver(matches) + deliver(re.pad(matches)) i++ } } @@ -1207,7 +624,7 @@ func (re *Regexp) allMatches(s string, b []byte, n int, deliver func([]int)) { // Find returns a slice holding the text of the leftmost match in b of the regular expression. // A return value of nil indicates no match. func (re *Regexp) Find(b []byte) []byte { - a := re.doExecute(newInputBytes(b), 0) + a := re.doExecute(newInputBytes(b), 0, 2) if a == nil { return nil } @@ -1219,7 +636,7 @@ func (re *Regexp) Find(b []byte) []byte { // b[loc[0]:loc[1]]. // A return value of nil indicates no match. func (re *Regexp) FindIndex(b []byte) (loc []int) { - a := re.doExecute(newInputBytes(b), 0) + a := re.doExecute(newInputBytes(b), 0, 2) if a == nil { return nil } @@ -1232,7 +649,7 @@ func (re *Regexp) FindIndex(b []byte) (loc []int) { // an empty string. Use FindStringIndex or FindStringSubmatch if it is // necessary to distinguish these cases. func (re *Regexp) FindString(s string) string { - a := re.doExecute(newInputString(s), 0) + a := re.doExecute(newInputString(s), 0, 2) if a == nil { return "" } @@ -1244,7 +661,7 @@ func (re *Regexp) FindString(s string) string { // itself is at s[loc[0]:loc[1]]. // A return value of nil indicates no match. func (re *Regexp) FindStringIndex(s string) []int { - a := re.doExecute(newInputString(s), 0) + a := re.doExecute(newInputString(s), 0, 2) if a == nil { return nil } @@ -1256,7 +673,7 @@ func (re *Regexp) FindStringIndex(s string) []int { // the RuneReader. The match itself is at s[loc[0]:loc[1]]. A return // value of nil indicates no match. func (re *Regexp) FindReaderIndex(r io.RuneReader) []int { - a := re.doExecute(newInputReader(r), 0) + a := re.doExecute(newInputReader(r), 0, 2) if a == nil { return nil } @@ -1269,13 +686,13 @@ func (re *Regexp) FindReaderIndex(r io.RuneReader) []int { // comment. // A return value of nil indicates no match. func (re *Regexp) FindSubmatch(b []byte) [][]byte { - a := re.doExecute(newInputBytes(b), 0) + a := re.doExecute(newInputBytes(b), 0, re.prog.NumCap) if a == nil { return nil } - ret := make([][]byte, len(a)/2) + ret := make([][]byte, 1+re.numSubexp) for i := range ret { - if a[2*i] >= 0 { + if 2*i < len(a) && a[2*i] >= 0 { ret[i] = b[a[2*i]:a[2*i+1]] } } @@ -1288,7 +705,7 @@ func (re *Regexp) FindSubmatch(b []byte) [][]byte { // in the package comment. // A return value of nil indicates no match. func (re *Regexp) FindSubmatchIndex(b []byte) []int { - return re.doExecute(newInputBytes(b), 0) + return re.pad(re.doExecute(newInputBytes(b), 0, re.prog.NumCap)) } // FindStringSubmatch returns a slice of strings holding the text of the @@ -1297,13 +714,13 @@ func (re *Regexp) FindSubmatchIndex(b []byte) []int { // package comment. // A return value of nil indicates no match. func (re *Regexp) FindStringSubmatch(s string) []string { - a := re.doExecute(newInputString(s), 0) + a := re.doExecute(newInputString(s), 0, re.prog.NumCap) if a == nil { return nil } - ret := make([]string, len(a)/2) + ret := make([]string, 1+re.numSubexp) for i := range ret { - if a[2*i] >= 0 { + if 2*i < len(a) && a[2*i] >= 0 { ret[i] = s[a[2*i]:a[2*i+1]] } } @@ -1316,7 +733,7 @@ func (re *Regexp) FindStringSubmatch(s string) []string { // 'Index' descriptions in the package comment. // A return value of nil indicates no match. func (re *Regexp) FindStringSubmatchIndex(s string) []int { - return re.doExecute(newInputString(s), 0) + return re.pad(re.doExecute(newInputString(s), 0, re.prog.NumCap)) } // FindReaderSubmatchIndex returns a slice holding the index pairs @@ -1325,7 +742,7 @@ func (re *Regexp) FindStringSubmatchIndex(s string) []int { // by the 'Submatch' and 'Index' descriptions in the package comment. A // return value of nil indicates no match. func (re *Regexp) FindReaderSubmatchIndex(r io.RuneReader) []int { - return re.doExecute(newInputReader(r), 0) + return re.pad(re.doExecute(newInputReader(r), 0, re.prog.NumCap)) } const startSize = 10 // The size at which to start a slice in the 'All' routines. |